Firefox uses too many CPU resources - How to fix

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At times, Firefox may require significant CPU resources in order to download, process, and display web content. If you are experiencing periods of sustained high CPU usage while using Firefox, this article presents some options for you to review.

The CPU (Central Processing Unit) is the "brain" of the computer. When the CPU is being heavily used, the overall performance of the computer can be impacted.

Depending on your operating system, you can review and monitor CPU usage through specific tools. On Windows, the Performance tab of the Windows Task Manager displays the rate of CPU consumption.

Note: If you send performance data, Mozilla will gather data including the CPU usage for your Firefox, which will help making Firefox better for future versions.

Updating to the latest version

Extensions and themes

Disabling CPU consuming extensions and themes

Extensions and themes can cause Firefox to use more CPU than it normally would.

To determine if an extension or theme is causing Firefox to use too much CPU, start Firefox in its Safe Mode and observing its CPU usage. In Safe Mode, extensions and themes are disabled, so if you notice a significant improvement, you can try disabling or uninstalling extensions.

Hiding intrusive content

Many web pages have content you don't need, such as ads, but which still use CPU resources to display its contents (see the plugin section below). To prevent automatic loading of unwanted Flash content, use the "Ask to Activate" setting in the Add-ons Manager Plugins panel. See the Set Adobe Flash to "click to play" on Firefox article for details.

Checking Firefox hardware acceleration

Corrupt content-prefs.sqlite file

Firefox stores your data in various files in your profile folder. The file used for saving individual website settings might be corrupt. If you delete that file, your zoom level settings will be reset, but it should decrease CPU usage.